Optimizing the synthesis of Ag/γ-Al2O3 for selective reduction of NOx with C3H6: Experiments and modelling

Ag/?-Al2O3 is an effective catalyst for the selective reduction of NOx (SCR) using propylene as a reducing agent. The catalyst performance is greatly influenced by the synthesis procedure. Various methods for synthesis of Ag/?-Al2O3 are analyzed, and their performance is examined via packed bed reactor experiments in this work. An optimal one-pot synthesis method, single-step sol-gel (SSG) synthesis, is explored systematically. The SSG-synthesized catalyst shows better performance than those prepared via wet impregnation. The influence of synthesis conditions, specifically pH, on the textural and morphological properties of the SSG-synthesized Ag/?-Al2O3, and therefore the activity for hydrocarbon-based SCR in a packed-bed reactor, are analyzed using experiments and simulations. The optimized catalyst demonstrates excellent performance (90% NOx conversion) for NOx reduction under nominal operating conditions with a wide activity temperature window (300-600 degrees C). The catalyst shows good time-on-stream performance and is effective at higher inlet oxygen concentrations and space velocities. A global kinetic model, which uses synthesis-pH-dependent parameters, is proposed, and its ability to predict the activities of these catalysts is validated.